Structural Analysis of Tanning Metallic Heterocomplexes and Testing their Tanning Properties
Pp. 95-122 (28)
Knowing the structure of tanning metallic heterocomplexes is closely linked
to their chemical properties in relation to stability in various environments specific for
natural leather tanning and to their ionic nature which influences their penetration in the
dermis of natural leathers. This chapter deals with specific analyses for coordination
complexes, for the purpose of anticipating the behaviour of tanning metallic
heterocomplexes upon the interaction with natural leather. IR and electron spectroscopy
have enabled to identify organic ligands, the polynuclearity of complexes by means of
sulphate or hydroxyl anions, the metal-oxygen-metal interactions and have eliminated
the hypothesis of direct metal-metal interactions. Electron spin resonance spectroscopy
allowed identification of structures in predominantly octahedral environments with rare
insertions of tetrahedral environments, which provides steric stability to heterocomplex
structures. SEM-EDAX analysis determines the existence of tanning metals used and
morphological particularities at microscopic level. Analysis of ionic components
explains the more pregnant anionic nature compared to that of the best known tanning
agent, basic chromium salt, and therefore, the improved efficiency of using tanning
metallic heterocomplexes in natural leather tanning.
IR spectroscopy, Electron spectroscopy, Electron spin resonance
spectroscopy, SEM-EDAX, Ion exchange chromatography, Tanning properties.
Leather and Footwear Research Institute Bucharest Romania.